The amazing 3Doodler 3D printing pen seems to be rather popular: it's Kickstarter fundraising campaign has now passed the USD$2M mark and it's still rising.
At this rate, the USD$75 handheld 3D printing device could potentially raise USD$4M or more. Now that's a lot of 3D pens!
More importantly, if there are suddenly 50,000+ 3D printing pens in the world, there are also suddenly 50,000+ additional plastic filament customers that will need a supply. Perhaps this is a good time to stock up on a few spools?